This study will investigate the prevalence of sleep apnea in a primary care clinic population. We will screen for sleep apnea in general medicine clinic patients using several diagnostic strategies: sleep history questionnaire, pulse oximetry, and portable nocturnal polysomnogram. The sensitivity, specificity, predictive value and cost-effectiveness of the different strategies will be compared using the portable polysomnography data as gold standard. The quality of life in those with and without sleep apnea will also be compared.